This invention relates to carbon dioxide (CO2) detectors. More particularly, it refers to a device containing CO2 calorimetric indicator paper, the device attached to an endotracheal tube for detecting CO2 levels in the breath of a patient following intubation.
U.S. Pat. No. 4,691,701 describes an early portable CO2 detector in the form of a transparent disc containing a chemical substance exhibiting a color change indication when exposed to carbon dioxide from a patient.
U.S. Pat. Nos. 5,197,464 and 5,291,879 describe methods of monitoring CO2 levels in a patient using a reversible indicator solution so that the indicator changes color continuously with the breathing of a patient.
Other references that include references to CO2 color change devices are U.S. Pat. Nos. 4,790,327; 4,928,687; 4,994,117; 5,005,572; 5,166,075; 5,179,002; 5,846,836 and 5,965,061.
A critical step in the intubation of a patient is a determination that the breathing tube or intubation tube or endotracheal tube is placed in the trachea and not in the esophagus. If the tube is in the esophagus, there is no return of CO2 from a patient""s breath. If the tube is in the trachea, CO2 will be present up to about five percent concentration. Since it is common in emergency situations for less highly skilled technicians to apply endotracheal tubes attached to a cardiopulmonary resuscitator (CPR) to a patient""s airway, it is important to have a portable single patient breathing apparatus such as a CPR containing a device confirming the proper initial placement and continuous placement of the endotracheal tube. A CO2 detector communicating with a CPR bag apparatus serves this purpose. Although such detector""s exist, alternate detectors which provide ease of use, low cost and connection to existing CPR apparatus is needed.
The invention described herein is an improvement over prior CO2 detectors used with CPR bags to ventilate patients. This CO2 detector has an easily mountable colorimetric indicator paper that continues to change color over several days in response to a patient""s exhaled breath. It is easily mountable in communication with a CPR bag, is lightweight and gives easily readable and reliable CO2 detection.
The inventive CO2 detector has a top housing integral with an inhale/exhale port. This port is connected to a CPR bag. A clear plastic disc is mounted to the top housing. The clear plastic disc is integral with a disc support containing snap legs engageable to complimentary grooves on the circumference of a bore through the top housing. Indicator paper is mounted on the inside surface of the plastic disc. Backing paper on the indicator paper is removed by pulling on the backing paper protruding from a slot below the disc. A bottom housing is glued or heat welded to the housing cover after a filter and baffle are mounted between the top housing and the bottom housing containing a downwardly directed port. This bottom housing port is connected to an intubation tube leading to a patient""s trachea. Provided the tube is properly placed, the breath of the patient will cause a color change on the calorimetric indicator paper viewed through the clear plastic cover of the CO2 detector of this invention.